Swaging method and swaging apparatus

ABSTRACT

An upsetting method capable of reducing a molding pressure is provided. The upsetting method uses a receiving die  11  and a guide  20  having an insertion hole  23  for inserting and holding a diameter expansion scheduled portion  2  of the raw material  1  in a buckling prevented state and in an axially slidable manner, the insertion hole being penetrated from the basal end to the tip end of the guide  20 . The method includes a step of receiving the diameter expansion scheduled portion  2  of the raw material  1  by the receiving portion  13  of the receiving die  11  and disposing the diameter expansion scheduled portion  2  of the raw material  1  in the insertion hole  23  of the guide  20 , and a step of expanding a diameter of the diameter expansion scheduled portion  2  of the raw material  1  exposed between the tip end face  21   a  of the guide  20  and the receiving portion  13  of the receiving die  11  by moving the guide  20  in a direction opposite to a pressurizing direction of the diameter expansion scheduled portion  2  of the raw material  1  while pressurizing the diameter expansion scheduled portion  2  of the raw material  1  with a pressurizing means  30  in an axial direction, after the step of disposing the diameter expansion scheduled portion  2  of the raw material  1 . At the diameter expanding step, the diameter expansion is performed in a state in which a portion  2   a  of the diameter expansion scheduled portion  2  of the raw material  1  corresponding to a tip end portion  21  of the guide  20  is locally heated by the heating means  40.

TECHNICAL FIELD

The present invention relates to an upsetting method and an upsetting apparatus used in manufacturing a product, such as, e.g., an arm or a piston for vehicles (e.g., cars, railroad vehicles, etc.).

BACKGROUND ART

In general, in an upsetting process, if a bar-shaped raw material buckles during the process, the obtained upset forged product becomes defective in shape, which causes degradation in value as a product. Therefore, in order to prevent occurrence of such buckling, the following upsetting method has been conventionally proposed.

That is, in this method, a diameter expansion scheduled portion of a bar-shaped raw material is received and held by a receiving portion of a receiving die in a buckling prevented state with the diameter expansion scheduled portion inserted in an insertion hole penetrated in a guide in an axially slidable manner. Subsequently, the guide is moved in a direction opposite to a pressurizing direction of the diameter expansion scheduled portion of the raw material while pressurizing the diameter expansion scheduled portion of the raw material in the axial direction with a punch as a pressurizing means, to thereby radially outwardly expand the diameter expansion scheduled portion of the raw material exposed between the tip end face of the guide and the receiving portion of the receiving die (see e.g., Patent Documents 1 to 4). This upsetting method has an advantage that buckling of the diameter expansion scheduled portion of the raw material can be prevented.

Patent Document 1: JP H09-253782, A

Patent Document 2: JP H07-506768, A

Patent Document 3: JP 2005-59097, A

Patent Document 4: JP 2005-144554, A

DISCLOSURE OF THE INVENTION Problems to be Solved

The aforementioned conventional upsetting method had the following defects.

In detail, in the aforementioned upsetting method, a friction resistance is created between the diameter expansion scheduled portion of the raw material and the peripheral surface of the insertion hole of the guide when the diameter expansion scheduled portion of the raw material is slidably moved in the insertion hole during the process. The longer the length of the diameter expansion scheduled portion of the raw material disposed in the insertion hole, the more the friction resistance is increased. In the aforementioned upsetting method, in order to overcome the friction resistance, it is required to pressurize the diameter expansion scheduled portion with a punch under a molding pressure larger than such friction resistance. Pressurizing under such a large molding pressure, however, may often cause crashing of an end portion of the diameter expansion scheduled portion of a raw material pressurized by the punch within the insertion hole. In this case, some of the material of the diameter expansion scheduled portion of the raw material will be introduced into the gap between the punch and the insertion hole, resulting in an increased molding pressure. This in turn causes immovable of the punch in the insertion hole in the pressure direction, which may result in unprocessable.

Furthermore, even in the case of using a pressurizing means other than a punch, when pressurized with a large molding force, a raw material will expand radially outwardly in an insertion hole of a guide, which further increases the molding pressure. This requires a driving source for the pressing means that can generates extremely large molding pressure. As a result, the driving source should grow in size, resulting in an increased mounting space of the upsetting apparatus. In addition, the purchase cost for the upsetting apparatus increases.

The present invention was made to solve the aforementioned drawbacks, and aims to provide an upsetting method capable of reducing the molding pressure, an upset forged product obtained by the upsetting method, and an upsetting apparatus used for the upsetting method.

Other objects and advantages of the present invention will be apparent from the following preferable embodiments.

Means to Solve the Problems Problems to be Solved

The present invention provides the following means.

[1] An upsetting method using a receiving die having a receiving portion and a guide having an insertion hole for inserting and holding a diameter expansion scheduled portion of a raw material in a buckling prevented state and in an axially slidable manner and a raw material outlet portion which is one end opening of the insertion hole provided at a tip end face of the guide,

the upsetting method comprising:

a step of receiving the diameter expansion scheduled portion of the raw material by the receiving portion of the receiving die and disposing the diameter expansion scheduled portion of the raw material in the insertion hole of the guide; and

a step of expanding a diameter of the diameter expansion scheduled portion of the raw material exposed between the tip end face of the guide and the receiving portion of the receiving die by moving the guide in a direction opposite to a pressurizing direction of the diameter expansion scheduled portion of the raw material while pressurizing the diameter expansion scheduled portion of the raw material with a pressurizing means in an axial direction, after the step of disposing the diameter expansion scheduled portion of the raw material,

characterized in that, at the diameter expansion step, the diameter expansion is performed in a state in which a portion of the diameter expansion scheduled portion of the raw material corresponding to a tip end portion of the guide is locally heated by the heating means.

[2] The upsetting method as recited in the aforementioned Item 1,

wherein the heating means is an induction heating means having an induction heating coil, and

wherein, at the diameter expansion step, the diameter expansion is performed in a state in which the portion of the diameter expansion scheduled portion of the raw material corresponding to the tip end portion of the guide is inductively heated with the induction heating coil arranged at the tip end portion of the guide.

[3] The upsetting method as recited in the aforementioned Item 1,

wherein the heating means is an induction heating means having an induction heating coil, and

wherein, at the diameter expansion step, the diameter expansion is performed in a state in which the portion of the diameter expansion scheduled portion of the raw material corresponding to the tip end portion of the guide is heated by inductively heating the tip end portion of the guide with the induction heating coil arranged at the tip end portion of the guide.

[4] The upsetting method as recited in the aforementioned Item 2 or 3, wherein the tip end portion of the guide having the induction heating coil is connected to a main body of the guide via a heat insulating layer.

[5] The upsetting method as recited in any one of the aforementioned Items 1 to 4, wherein, at the diameter expansion step, the diameter expansion is performed in a state in which the portion of the diameter expansion scheduled portion of the raw material corresponding to the tip end portion of the guide is heated into a half molten state.

[6] The upsetting method as recited in any one of the aforementioned Items 1 to 5, wherein, at the diameter expansion step, the diameter expansion is performed in a state in which an inner surface of a portion of the insertion hole located at a basal end side of the guide relative to the tip end portion of the guide is cooled with a first cooling means

[7] The upsetting method as recited in the aforementioned Item 1,

wherein a molding portion having a cavity for molding the diameter expansion scheduled portion of the raw material into a designed shape is extended from the receiving portion of the receiving die,

wherein, at the step of disposing the diameter expansion scheduled portion of the raw material, the diameter expansion scheduled portion of the raw material is received by the receiving portion of the receiving die, the diameter expansion scheduled portion of the raw material is disposed in the insertion hole of the guide, and the tip end portion of the guide is disposed in the cavity of the receiving die, and

wherein, at the diameter expansion step, the diameter expansion scheduled portion of the raw material exposed between the tip end face of the guide and the receiving portion of the receiving die is expanded in diameter in the cavity of the receiving die.

[8] The upsetting method as recited in the aforementioned Item 7, wherein, at the diameter expansion step, the diameter expansion is performed in a state in which a molding surface of the cavity of the receiving die is cooled with a second cooling means.

[9] An upset forged article obtained by the upsetting method as recited in any one of the aforementioned Items 1 to 8.

[10] An upsetting method using a receiving die having receiving portions formed at both axial end portions and a holding hole communicating with both the receiving portions for holding a non-diameter-expansion scheduled portion of a raw material and two guides each having an insertion hole for inserting and holding a diameter expansion scheduled portion of the raw material located at an axial end side in a buckling prevented manner and in an axially slidable manner with respect to the non-diameter-expansion scheduled portion of the raw material and each having a raw material outlet portion constituted by one end opening of the insertion hole provided at the tip end face,

the upsetting method comprising:

a step of receiving each diameter expansion scheduled portion of the raw material by a corresponding receiving portion of the receiving die by disposing the non-diameter-expansion scheduled portion of the raw material in the holding hole of the receiving die and disposing both the diameter expansion scheduled portions of the raw material in the insertion holes of the guide respectively; and

a step of simultaneously expanding both the diameter expansion scheduled portions of the raw material exposed between the tip end face of each guide and the corresponding receiving portions of the receiving die by moving each guide in a direction opposite to a pressurizing direction of the corresponding diameter expansion scheduled portion of the raw material while pressurizing both the diameter expansion scheduled portions of the raw material with the pressuring means in the axial direction respectively, characterized in that, at the diameter expansion step, the diameter expansion is performed in a state in which a portion of each diameter expansion scheduled portion of the raw material corresponding to a tip end portion of the guide is locally heated with a heating means.

[11] The upsetting method as recited in the aforementioned Item 10,

wherein the heating means is an induction heating means having an induction heating coil, and

wherein, at the diameter expansion step, the diameter expansion is performed in a state in which the portion of each diameter expansion scheduled portion of the raw material corresponding to the tip end portion of each guide is inductively heated with the induction heating coil disposed at the tip end portion of each guide.

[12] The upsetting method as recited in the aforementioned Item 10,

wherein the heating means is an induction heating means having an induction heating coil, and

wherein, at the diameter expansion step, the diameter expansion is performed in a state in which the portion of each diameter expansion scheduled portion of the raw material corresponding to the tip end portion of each guide is heated by inductively heating the tip end portion of each guide with the induction heating coil disposed at the tip end portion of each guide.

[13] The upsetting method as recited in the aforementioned Item 11 or 12, wherein the tip end portion of each guide having the induction heating coil is connected to a main body of the guide via a heat insulating layer.

[14] The upsetting method as recited in any one of the aforementioned Items 10 to 13, wherein, at the diameter expansion step, the diameter expansion is performed in a state in which the portion of each diameter expansion scheduled portion of the raw material corresponding to the tip end portion of each guide is heated into a half molten state.

[15] The upsetting method as recited in any one of the aforementioned Items 10 to 14, wherein, at the diameter expansion step, the diameter expansion is performed in a state in which an inner surface of a portion of the insertion hole located at a basal end side of each guide relative to the tip end portion of the guide is cooled with a first cooling means.

[16] The upsetting method as recited in any one of the aforementioned Items 10 to 15,

wherein a molding portion having a cavity for molding the diameter expansion scheduled portion of the raw material into a designed shape is extended from each receiving portion of the receiving die,

wherein, at the step of disposing the diameter expansion scheduled portion of the raw material, each diameter expansion scheduled portion of the raw material is received by the receiving portion of the receiving die by disposing the non-diameter-expansion scheduled portion of the raw material in the holding hole of the receiving die, both the diameter expansion scheduled portions of the raw material are disposed in the insertion hole of the guide respectively, and the tip end portions of the guides are disposed in the cavities of the receiving die respectively, and

wherein, at the diameter expansion step, both the diameter expansion scheduled portions of the raw material exposed between the tip end face of each guide and each receiving portion of the receiving die are simultaneously expanded in diameter in the corresponding cavity of the receiving die respectively.

[17] The upsetting method as recited in the aforementioned Item 16, wherein, at the diameter expansion step, the diameter expansion is performed in a state in which a molding surface of each cavity of the receiving die is cooled with a second cooling means.

[18] An upset forged article obtained by the upsetting method as recited in any one of the aforementioned Items 10 to 17.

[19] An upsetting apparatus, comprising:

a receiving die having a receiving portion for receiving a diameter expansion scheduled portion of a raw material;

a guide having an insertion hole for inserting and holding the diameter expansion scheduled portion of the raw material in a buckling prevented state and in an axially slidable manner and a raw material outlet portion constituted by one end opening of the insertion hole formed at a tip end face;

pressurizing means for pressurizing the diameter expansion scheduled portion of the raw material disposed in the insertion hole of the guide in an axial direction; and

guide driving means for moving the guide in a direction opposite to a pressurizing direction of the diameter expansion scheduled portion of the raw material,

wherein it is configured such that the diameter expansion scheduled portion of the raw material exposed between the tip end face of the guide and the receiving portion of the receiving die is expanded in diameter, and

characterized in that the upsetting apparatus further comprises a heating means for locally heating a portion of the diameter expansion scheduled portion of the raw material corresponding to a tip end portion of the guide.

[20] The upsetting apparatus as recited in the aforementioned Item 19,

wherein the heating means is an induction heating means having an induction heating coil, and

wherein it is configured to inductively heat the portion of the diameter expansion scheduled portion of the raw material corresponding to the tip end portion of the guide by the induction heating coil disposed at the tip end portion of the guide.

[21] The upsetting apparatus as recited in the aforementioned Item 19,

wherein the heating means is an induction heating means having an induction heating coil, and

wherein it is configured to heat the portion of the diameter expansion scheduled portion of the raw material corresponding to the tip end portion of the guide by inductively heating the tip end portion of the guide with the induction heating coil disposed at the tip end portion of the guide.

[22] The upsetting apparatus as recited in the aforementioned Item 20 or 21, wherein the tip end portion of the guide having the induction heating coil is connected to a main body of the guide via a heat insulating layer.

[23] The upsetting apparatus as recited in any one of the aforementioned Items 19 to 22, wherein the heating means is capable of heating the portion of the diameter expansion scheduled portion of the raw material corresponding to the tip end portion of the guide into a half molten state.

[24] The upsetting apparatus as recited in any one of the aforementioned Items 19 to 23, further comprising a first cooling means for cooling an inner surface of a portion of the insertion hole located at a basal end side of the guide relative to the tip end portion of the guide.

[25] The upsetting apparatus as recited in any one of the aforementioned Items 19 to 24,

wherein a molding portion having a cavity for molding the diameter expansion scheduled portion of the raw material into a designed shape is extended from the receiving portion of the receiving die, and

wherein it is configured to expand a diameter of the diameter expansion scheduled portion of the raw material exposed between the tip end face of the guide and the receiving portion of the receiving die within the cavity of the receiving die.

[26] The upsetting apparatus as recited in the aforementioned Item 25, further comprising a second cooling means for cooling a molding surface of the cavity of the receiving die.

[27] An upsetting apparatus, comprising:

a receiving die having receiving portions formed at both axial end portions and a holding hole communicating with both the receiving portions for holding a non-diameter-expansion scheduled portion of a raw material;

two guides each having an insertion hole for inserting and holding a diameter expansion scheduled portion of the raw material located at an axial end side in a buckling prevented state and in an axially slidable manner with respect to the non-diameter-expansion scheduled portion of the raw material and each having a raw material outlet portion constituted by one end opening of the insertion hole formed at the tip end face;

two pressurizing means each for pressurizing the diameter expansion scheduled portion of the raw material disposed in the insertion hole of each guide in the axial direction;

two guide driving means each for moving each guide in a direction opposite to a pressurizing direction of the corresponding diameter expansion scheduled portion of the raw material,

wherein it is configured to simultaneously expand diameters of both the diameter expansion scheduled portions of the raw material exposed between the tip end face of each guide and the corresponding receiving portion of the receiving die,

characterized in that the upsetting apparatus further comprises two heating means for locally heating a portion of each diameter expansion scheduled portion of the raw material corresponding to a tip end portion of the guide.

[28] The upsetting apparatus as recited in the aforementioned Item 27,

wherein each heating means is an induction heating means having an induction heating coil, and

wherein it is configured to inductively heat the portion of each diameter expansion scheduled portion of the raw material corresponding to the tip end portion of each guide by the induction heating coil disposed at a tip end portion of each guide.

[29] The upsetting apparatus as recited in the aforementioned Item 27,

wherein each heating means is an induction heating means having an induction heating coil, and

wherein it is configured to heat the portion of each diameter expansion scheduled portion of the raw material corresponding to the tip end portion of each guide by inductively heating the tip end portion of each guide with the induction heating coil disposed at the tip end portion of each guide.

[30] The upsetting apparatus as recited in the aforementioned Item 28 or 29, wherein the tip end portion of each guide having the induction heating coil is connected to a main body of each guide via a heat insulating layer.

[31] The upsetting apparatus as recited in any one of the aforementioned Items 27 to 30, wherein each heating means is capable of heating the portion of the diameter expansion scheduled portion of the raw material corresponding to the tip end portion of each guide into a half molten state.

[32] The upsetting apparatus as recited in any one of the aforementioned Items 27 to 31, further comprising a first cooling means for cooling an inner surface of a portion of the insertion hole of each guide located at a basal end side of the guide relative to the tip end portion of the guide.

[33] The upsetting apparatus as recited in any one of the aforementioned Items 27 to 32,

wherein a molding portion having a cavity for molding the diameter expansion scheduled portion of the raw material into a designed shape is extended from each receiving portion of the receiving die, and

wherein it is configured to simultaneously expand diameters of both the diameter expansion scheduled portions of the raw material exposed between the tip end face of each guide and each receiving portion of the receiving die within each cavity of the receiving die.

[34] The upsetting apparatus as recited in the aforementioned Item 33, further comprising a second cooling means for cooling a molding surface of each cavity of the receiving die.

EFFECTS OF THE INVENTION

According to the invention of the aforementioned Item [1], since the upsetting method includes a step of receiving the diameter expansion scheduled portion of the raw material by the receiving portion of the receiving die and disposing the diameter expansion scheduled portion of the raw material in the insertion hole of the guide, and a step of expanding a diameter of the diameter expansion scheduled portion of the raw material exposed between the tip end face of the guide and the receiving portion of the receiving die by moving the guide in a direction opposite to a pressurizing direction of the diameter expansion scheduled portion of the raw material while pressurizing the diameter expansion scheduled portion of the raw material with a pressurizing means in an axial direction, after the step of disposing the diameter expansion scheduled portion of the raw material, the buckling of the diameter expansion scheduled portion of the raw material can be prevented.

Furthermore, at the diameter expansion step, since only the portion of the diameter expansion scheduled portion of the raw material corresponding to the tip end portion of the guide will be locally deteriorated in deformation resistance by locally heating the portion of the diameter expansion scheduled portion of the raw material corresponding to the tip end portion of the guide with the heating means, the molding pressure can be reduced.

On the other hand, the portion of the diameter expansion scheduled portion of the raw material located at the basal end side of the guide relative to the tip end portion thereof does not decrease in deformation resistance. This can prevent an increase of the molding pressure caused by a radially outward expansion of the raw material within the insertion hole of the guide and an increase of the molding pressure caused by introduction of a part of the material of the diameter expansion scheduled portion of the raw material into the gap between the pressurizing member of the pressurizing means (e.g., a punch) and the insertion hole.

According to the present invention as recited in the aforementioned Item [2], the portion of the diameter expansion scheduled portion of the raw material corresponding to the tip end portion of the guide can be heated assuredly in an extremely efficient manner.

According to the present invention as recited in the aforementioned Item [3], the portion of the diameter expansion scheduled portion of the raw material corresponding to the tip end portion of the guide can be heated assuredly in an efficient manner.

According to the present invention as recited in the aforementioned Item [4], it can be restrained to transfer the heat of the tip end portion of the guide to the main body of the guide by the heat insulating layer. Therefore, it can be assuredly prevented that the portion of the diameter expansion scheduled portion of the raw material located at the basal side with respect to the tip end portion of the guide is heated.

According to the present invention as recited in the aforementioned Item [5], the molding pressure can be remarkably reduced.

According to the present invention as recited in the aforementioned Item [6], it can be assuredly prevented that the portion of the diameter expansion scheduled portion of the raw material located at the basal end side of the guide relative to the tip end portion of the guide is heated.

According to the present invention as recited in the aforementioned Item [7], the upsetting method for expanding the diameter expansion scheduled portion of the raw material in diameter within the cavity, i.e., the restriction upset forming method, has the aforementioned effects.

Furthermore, by heating the portion of the diameter expansion scheduled portion of the raw material corresponding to the tip end portion of the guide, the plastic flow of the material of the diameter expansion scheduled portion in the cavity will be enhanced. As a result, even in cases where the configuration of the cavity is complex, the material of the diameter expansion scheduled portion can be sequentially filled in the cavity, and a diameter expanded portion having no material-lacked portion can be formed.

According to the present invention as recited in the aforementioned Item [8], at the time of the diameter expansion, the crystal growth in the diameter expansion scheduled portion of the raw material within the cavity of the receiving die can be restrained.

According to the present invention as recited in the aforementioned Item [9], the aforementioned effects can be attained in manufacturing an upset forged article.

According to the present invention as recited in the aforementioned Item [10], the same effects as mentioned in the aforementioned Item [1] can be attained. Furthermore, an upset forged article having diameter expanded portions at both the axial side portions can be manufactured efficiently.

According to the present invention as recited in the aforementioned Item [11], the same effects as mentioned in the aforementioned Item [2] can be attained.

According to the present invention as recited in the aforementioned Item [12], the same effects as mentioned in the aforementioned Item [3] can be attained.

According to the present invention as recited in the aforementioned Item [13], the same effects as mentioned in the aforementioned Item [4] can be attained.

According to the present invention as recited in the aforementioned Item [14], the same effects as mentioned in the aforementioned Item [5] can be attained.

According to the present invention as recited in the aforementioned Item [15], the same effects as mentioned in the aforementioned Item [6] can be attained.

According to the present invention as recited in the aforementioned Item [16], the same effects as mentioned in the aforementioned Item [7] can be attained.

According to the present invention as recited in the aforementioned Item [17], the same effects as mentioned in the aforementioned Item [8] can be attained.

According to the present invention as recited in the aforementioned Item [18], the aforementioned effects as mentioned can be attained in manufacturing an upset forged article having diameter expanded portions at both the axial side portions.

According to the present inventions as recited in the aforementioned Items [19] to [26], an upsetting apparatus preferably used for the upsetting method according to any one of the inventions as recited in the aforementioned Items [1] to [8].

According to the present inventions as recited in the aforementioned items [27] to [34], an upsetting apparatus preferably used for the upsetting method according to any one of the inventions as recited in the aforementioned Items [10] to [17].

BRIEF EXPLANATION OF THE DRAWINGS

FIG. 1 is a perspective view showing a guide of an upsetting apparatus according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view of the guide showing a state in which a diameter expansion scheduled portion of a raw material is disposed in an insertion hole of the guide.

FIG. 3 is a cross-sectional view of the upsetting apparatus in a state before expanding the diameter expansion scheduled portion of the raw material.

FIG. 4 is a cross-sectional view of the upsetting apparatus in a state in which the diameter expansion scheduled portion of the raw material is being expanded in diameter.

FIG. 5 is a cross-sectional view of the upsetting apparatus in a state after expanding the diameter expansion scheduled portion of the raw material.

FIG. 6 is a perspective view of an upsetting article formed by the upsetting apparatus.

FIG. 7 is an explanatory view of the upsetting apparatus according to the second embodiment of the present invention and a cross-sectional view of the upsetting apparatus in a state before expanding the diameter expansion scheduled portion of the raw material.

FIG. 8 is a cross-sectional view of the upsetting apparatus in the middle of expanding the diameter expansion scheduled portion of the raw material.

FIG. 9 is a cross-sectional view of the upsetting apparatus in a state after expanding the diameter expansion scheduled portion of the raw material.

FIG. 10 is a perspective view of an upset forged article formed by the upsetting apparatus.

DESCRIPTION OF REFERENCE NUMERALS

-   1 . . . material -   2 . . . diameter expansion scheduled portion -   3 . . . non-diameter-expansion scheduled portion -   5A, 5B . . . upset forged article -   6 . . . diameter expanded portion -   10A, 10B . . . upsetting apparatus -   11 . . . receiving die -   12 . . . holding hole -   13 . . . receiving portion -   14 . . . molding portion -   15 . . . cavity -   20 . . . guide -   21 . . . tip end portion of the guide -   22 . . . guide main body -   23 . . . insertion hole -   23 a . . . raw material outlet portion -   24 . . . heat insulating layer -   27 . . . guide driving means -   30 . . . pressurizing means -   31 . . . punch -   32 . . . punch driving means -   40 . . . heating means -   41 . . . induction heating means -   42 . . . induction heating coil -   43 . . . power source portion -   50 . . . first cooling means -   51 . . . cooling liquid passage -   55 . . . second cooling means -   56 . . . cooling jacket -   S . . . diameter expanded space

BEST MODE FOR CARRYING OUT THE INVENTION

Next, some preferable embodiments of the present invention will be explained with reference to the drawings.

FIGS. 1 to 5 are explanatory drawings of an upsetting apparatus 10A and an upsetting method according to a first embodiment of the present invention. In FIG. 3, “1” denotes a bar-shaped raw material.

In FIG. 6, “5A” denotes an upset forged article obtained by an upsetting method using the upsetting apparatus 10A of the first embodiment. This upset forged article 5A has diameter expanded portions 6 each having an approximately spindle-shape (or approximately oval sphere-shape) and integrally formed at axial ends of a bar-shaped shaft 7. The shaft portion 7 is straight. Each diameter expanded portion 6 is formed to have an even thickness increased in the peripheral direction thereof.

This upset forged article 5A is used as a preform for manufacturing a prescribed product. Accordingly, in the present invention, the upsetting apparatus 10A can be recognized as a preform manufacturing apparatus, and the upsetting method can be recognized as a preform manufacturing method.

In this embodiment, this upset forged article 5A can be used as a preform for manufacturing, for example, a vehicle arm for use in, e.g., an automobile or a railroad vehicle. Each diameter expanded portion 6 of this upset forged article 5A is a portion which will be subjected to after processing to form a connecting portion (e.g., bush mounting portion or york portion) to be connected to another member. In the present invention, this upset forged article 5A can be an article to be used as, other than a preform for manufacturing a vehicle arm, a preform for manufacturing, for example, a double-headed piston for a compressor, etc.

The raw material 1 is a bar-shaped member as shown in FIG. 3, more specifically a straight solid round bar-shaped member. The raw material 1 is made of a metallic material, more specifically aluminum or aluminum alloy material. The cross-sectional shape of the raw material 1 is round, and the diameter of the raw material 1 is set to be constant in the axial direction.

The axial central portion of this raw material 1 is a non-diameter-expansion scheduled portion 3. The portions of the raw material 1 located at axial both sides with respect to the non-diameter-expansion scheduled portion 3, i.e., axial end portions of this raw material 1, are diameter expansion scheduled portions 2. The non-diameter-expansion scheduled portion 3 of the raw material 1 corresponds to the shaft portion 7 of the upset forged article 5A.

In the present invention, material of the raw material 1 is not limited to aluminum or aluminum alloy, and can be, for example, brass, copper (including its alloy), or steel, or can be plastic. The cross-sectional shape of the raw material 1 is not limited to a round shape, and can be, for example, a polygonal shape, such as, e.g., a quadrangular shape or a hexagonal shape. Further, the raw material 1 can be made of, for example, an extruded member, or can be a continuously casted rolled member manufactured by a properch method etc., or can be a member manufactured by any other methods.

The length of the raw material 1 is, for example, 50 to 1,000 mm, and the diameter is, for example, 10 to 30 mm (more specifically 16 mm or the like). In the upset forged article 5A, for example, the maximum diameter of the diameter expanded portion 6 is 30 to 100 mm (more specifically 50 mm or the like), and the length of the diameter expanded portion 6 is 10 to 100 mm, and the length of the shaft portion 7 is 20 to 300 mm (more specifically 160 mm or the like). In the invention, however, the size of the raw material 1 and the size of each portion of the upset forged article 5A are not limited to the aforementioned sizes. For example, the size of the raw material 1 and the size of each portion of the upset forged article 5A can be set so as to attain objects of the present invention in accordance with the production of the desired product, such as, e.g., a vehicle arm.

As shown in FIG. 3, the upsetting apparatus 10A is equipped with a receiving die 11, two guides 20 and 20, two heating means 40 and 40, two pressurizing means 30 and 30, and two guide driving means 27 and 27.

The receiving die 11 is provided with receiving portions 13 at the axial both ends. Each receiving portion 13 is configured to receive the diameter expansion scheduled portion 2 of the raw material 1, or more specifically to receive the material of the diameter expansion scheduled portion 2 at the time of expanding the diameter of each diameter expansion scheduled portion 2 of the raw material 1.

This receiving die 11 has a holding hole 12 extending in the axial direction and communicated with both the receiving portions 13 and 13. Thus, each receiving portion 13 has an end opening of the holding hole 12. This holding hole 12 is configured to hold the non-diameter-expansion scheduled portion 3 of the raw material 1 in a buckling prevented state and in an axial movement prevented state. This holding hole 12 can also be recognized as a raw material attaching hole for attaching the raw material 1 to the receiving portions 13. The cross-sectional shape of the holding hole 12 corresponds to the cross-sectional shape of the non-diameter-expansion scheduled portion 3 of the raw material 1, i.e., a round cross-sectional shape. The diameter of the holding hole 12 is set to be approximately the same as the diameter of the non-diameter-expansion scheduled portion 3 of the raw material 1.

Furthermore, the receiving die 11 is divided into a plurality of members (e.g., two pieces of members) with dividing surfaces (not shown) perpendicular to the holding hole 12. Thus, by disposing the non-diameter-expansion scheduled portion 3 of the raw material 1 between the divided grooves of the holding hole 12 of the plurality of divided members constituting the holding hole 12, and then combining the plurality of divided members to unify them, the non-diameter-expansion scheduled portion 3 of the raw material 1 is disposed in the holding hole 12 in a slightly tightly fitted manner. With this, each diameter expansion scheduled portion 3 of the raw material 1 is received by the corresponding receiving portion 13 of the receiving die 11, and the non-diameter-expansion scheduled portion 3 of the raw material 1 is held in the holding hole 12 in a buckling prevented state and in the axial movement prevented state.

Two guides 20 and 20 are the same in structure. Each guide 20 has, as shown in FIG. 2, an insertion hole 23 for axially inserting and holding the corresponding diameter expansion scheduled portion 2 of the raw material 1 in a buckling prevented state. This insertion hole 23 is penetrated from the basal end of the guide 20 to the tip end thereof. Therefore, as shown in FIGS. 1 and 2, at the tip end face 21 a of the guide 20, a raw material outlet portion 23 a which is one end opening portion of the insertion hole 23 is provided. While, at the basal end face of the guide 20, a raw material inlet portion which is the other end opening portion of the insertion hole 23 is provided.

This insertion hole 23 is designed for guiding the diameter expansion scheduled portion 2 of the raw material 1 inserted and disposed in the insertion hole 23 to the diameter expanding space S between the tip end face 21 a of the guide 20 and the receiving portion 13 of the receiving die 11. In this first embodiment, this diameter expanding space S is a space in which the diameter expansion scheduled portion 2 of the raw material 1 can be freely expanded in diameter, i.e., a free diameter expanding space.

The cross-sectional shape of the insertion hole 23 of the guide 20 is a shape corresponding to the cross-sectional shape of the diameter expansion scheduled portion 2 of the raw material 1, i.e., a round cross-sectional shape. Furthermore, the diameter of the insertion hole 23 is set to be the same as or slightly larger than the diameter of the diameter expansion scheduled portion 2 of the raw material 1. With this, the insertion hole 23 is configured such that the diameter expansion scheduled portion 2 of the raw material 1 can be inserted and disposed in the insertion hole 23 in a buckling prevented state and in an axially slidably movable manner.

Furthermore, as shown in FIGS. 1 and 2, the tip end portion 21 of the guide 20 is formed to be smaller in diameter than the basal end side portion of the guide 20. In this embodiment, the basal end side portion of the guide 20 will be referred to as a “guide main body 22.”

The two heating means 40 and 40 are the same in structure. As shown in FIG. 2, each heating means 40 is designed for locally heating the portion 2 a of the diameter expansion scheduled portion 2 of the raw material 1 corresponding to the tip end portion 21 of the guide 20. In this embodiment, each heating means 40 is an induction heating means 41 having an induction heating coil 42 and a power supplying portion 43 for supplying AC current (or AC voltage). Furthermore, the reference numeral “44” denotes a lead wire for connecting the induction heating coil 42 and the power supplying portion 43.

The induction heating coil 42 is arranged in the tip end portion 21 of the guide 20 so as to surround the insertion hole 23. In this embodiment, the induction heating coil 42 is embedded in the tip end portion 21 of the guide 20.

The tip end portion 21 of the guide 20 is formed by, for example, a hard nonconductive material having heat resistance such as ceramics, or a hard conductive material having heat resistance (e.g., heat resistant metallic material) such as steel material. On the other hand, the portion of the guide 20 located at the basal end side thereof relative to the tip end portion 21, i.e., the guide main body 22, is made of metallic material such as, e.g., steel material.

This induction heating means 41 is configured to locally inductively heat the portion 2 a of the diameter expansion scheduled portion 2 of the raw material 1 corresponding to the tip end portion 21 of the guide 20 by supplying current (applying voltage) having a prescribed frequency to the induction heating coil 42 by the power supplying portion 43. Further, this induction heating means 41 is configured to heat the portion 2 a of the diameter expansion scheduled portion 2 of the raw material 1 corresponding to the tip end portion 21 of the guide 20 in a half molten state by adjusting the current supplying amount or the like to the induction heating coil 42.

Furthermore, the tip end portion 21 of the guide 20 is integrally provided with a flange portion 21 b. This flange portion 21 b is arranged at the end portion of the guide main body 22 via a heat insulating layer 24. With this state, the flange portion 25, the heat insulating layer 24 and the guide main body 22 are mutually integrally connected with a plurality of connecting bolts 25 and 25. Thus, the tip end portion 21 of the guide 20 is connected to the guide main body 22 via the heat insulating layer 24. In this guide 20, the heat of the tip end portion 21 of the guide 20 is restrained from being conducted to the guide main body 22 by the heat insulating layer 24. The heat insulating layer 24 is made of, for example, an alumina plate or a zirconia plate.

Furthermore, this upsetting apparatus 10A is equipped with two first cooling means 50 and 50 for cooling the periphery of the insertion hole 23 in the guide main body 22 of each guide 20.

Both the first cooling means 50 and 50 are the same in structure. Each first cooling means 50 is configured to cool the peripheral surface of the insertion hole 23 in the guide main body 22 by passing a cooling liquid such as a cooling water through one or a plurality of cooling liquid passages 51 formed in the inside of the guide main body 50. “52 a” denotes a supplying pipe for supplying a cooling liquid to the cooling liquid passage 51, and “52 b” denotes a discharging pipe for discharging the cooling liquid from the cooling liquid passage 51. Further, “53” denotes a flow direction of the cooling liquid.

Two pressurizing means 30 and 30 are the same in structure. Each pressurizing means 30 is designed to pressurize each diameter expansion scheduled portion 2 of the raw material 1 inserted and disposed in the insertion hole 23 of the guide 20 in the axial direction. This pressurizing means 30 has a punch 31 and a punch driving portion 32 for driving the punch 31, and is configured to pressurize the diameter expansion scheduled portion 2 of the raw material 1 in the axial direction with the punch 31 by driving the punch 31 by the punch driving portion 32. As the driving source of the punch driving portion 32, for example, a fluid pressure cylinder (e.g., an oil cylinder or a gas pressure cylinder) can be used.

Both the guide driving means 27 and 27 are the same in structure. Each guide driving means 27 is designed to move the guide 20 in a direction opposite to the pressurizing direction of the corresponding diameter expansion scheduled portion 2 of the raw material 1. As the driving source of this guide driving means 27, for example, a fluid pressure cylinder (e.g., an oil cylinder or a gas pressure cylinder) can be used.

Next, an upsetting method using the upsetting apparatus 10A of this first embodiment will be explained below.

Initially, as shown in FIG. 3, the non-diameter-expansion scheduled portion 3 of the raw material 1 is inserted and disposed in the holding hole 12 of the receiving die 11. With this, each diameter expansion scheduled portion 2 of the raw material 1 is received by the corresponding receiving portion 13 of the receiving die 11, while the non-diameter-expansion scheduled portion 3 of the raw material 1 is held in the holding hole 12 in a buckling prevented state and in the axial movement prevented manner.

Furthermore, both the diameter expansion scheduled portions 2 of the raw material 1 are inserted and disposed in the corresponding insertion hole 23 of the guide, respectively [Disposing step of a raw material diameter expansion scheduled portion]. With this, each diameter expansion scheduled portion 2 of the raw material 1 is inserted and held in the insertion hole 23 in a buckling prevented state and in an axially slidably movable manner.

In this disposing step of the diameter expansion scheduled portion 2 of the raw material 1, as mentioned above, after receiving the diameter expansion scheduled portion 2 of the raw material 1 by inserting and disposing the non-diameter-expansion scheduled portion 3 of the raw material 1 in the holding hole 12 of the receiving die 11, the diameter expansion scheduled portion 2 of the raw material 1 can be inserted and disposed in the insertion hole 23 of the guide 20. Alternatively, after inserting and disposing the diameter expansion scheduled portion 2 of the raw material 1 in the insertion hole 23 of the guide 20, the diameter expansion scheduled portion 2 of the raw material 1 can be received by the receiving portion 13 of the receiving die 11 by inserting and disposing the non-diameter-expansion scheduled portion 3 of the raw material 1 in the holding hole 12 of the receiving die 11.

Furthermore, current of a prescribed frequency is supplied to the induction heating coil 42 of each induction heating means 41 by the power source portion 43 to locally inductively heat the portion 2 a of each diameter expansion scheduled portion 2 of the raw material 1 corresponding to the tip end portion 21 of the guide to a predetermined temperature.

This heating temperature can be any temperature at which the deformation resistance of the portion 2 a of the raw material 1 decreases, and not specifically limited. The preferable heating temperatures can be concretely exemplified as follows.

For example, in cases where the raw material 1 is made of aluminum or aluminum alloy, the preferable heating temperature range is, e.g., 200 to 580° C. (more preferably 350 to 540° C.). In the case of heating the prescribed portion 2 a of the raw material 1 into a half-molten state, the preferable heating temperature range is, e.g., 580 to 625° C. (more preferably 600 to 615° C.). The present invention does not require that the heating temperature falls within the aforementioned ranges.

Further, a cooling liquid, such as a cooling water, of a normal temperature is passed through the cooling liquid passage 51 of the guide main body 22 of each guide 20 to cool the periphery of the insertion hole 23 in the guide main body 22. Thus, the portion 2 b of the diameter expansion scheduled portion 2 of the raw material 1 located at the basal end side of the guide 20 relative to the tip end portion 21 of the guide 20 will be locally cooled to the predetermined temperature due to the contact with the periphery of the insertion hole 23.

In this case, the preferable cooling temperature range can be, for example, 30 to 85° C. (more preferably 40 to 60° C.). In the present invention, however, it is not required that the cooling temperature falls within the aforementioned ranges.

Subsequently, while keeping this state, each guide 20 is moved in a direction opposite to the pressurizing direction of the corresponding diameter expansion scheduled portion 2 of the raw material 1 with the guide driving means 27 while simultaneously pressurizing both the diameter expansion scheduled portions 2 of the raw material 1 with the corresponding punch 31 of the pressurizing means 30. With this, as shown in FIG. 4, both the diameter expansion scheduled portions 2 of the raw material 1 exposed between the tip end face 21 a of each guide 20 and the corresponding receiving portion 13 of the receiving die 11 are simultaneously expanded in diameter at the diameter expanding space S between the tip end face 21 a of each guide 20 and the receiving portion 13 of the receiving die 11 [Expansion Step]. In this first embodiment, the diameter expanding space S is a free diameter expanding space as mentioned above.

The moving speed of the guide 20 and the pressurizing speed of the diameter expansion scheduled portion 2 of the raw material 1 by the punch 31 are set in accordance with the diameter expansion designed configuration of the diameter expansion scheduled portion 2 of the raw material 1. These speeds can be constant or variable.

As shown in FIG. 5, when each diameter expansion scheduled portion 2 of the raw material 1 is formed into the designed shape, the movement of the guide 20 and the pressurization by the punch 31 are stopped.

Subsequently, by taking out the raw material 1 from the receiving die 11, the desired upset forged article 5A as shown in FIG. 6 can be obtained.

The diameter expanded portion 6 of the obtained upset forged article 5A as a preform is subjected to after processing according to need.

In this upsetting method, at the time of initiating the pressurization of the diameter expansion scheduled portion 2 of the raw material 1 by the punch 31, i.e., at the time of initiating the diameter expansion of the diameter expansion scheduled portion 2 of the raw material 1, the length of the diameter expansion scheduled portion 2 of the raw material 1 exposed between the tip end face 21 a of the guide 20 and the receiving portion 13 of the receiving die 11 is set to be not longer than the buckling limit length of the diameter expansion scheduled portion 2 (preferably shorter than the buckling limit length).

Further, in this upsetting method, a time lag can be set between the initiation of pressurization of the diameter expansion scheduled portion 2 of the raw material 1 by the punch 31 and the initiation of movement of the guide 20. By doing so, the cross-sectional area of the diameter expansion scheduled portion 2 is increased at the diameter expansion early stage, which can prevent buckling more assuredly.

Thus, the upsetting method of the first embodiment has the following effects.

That is, this upsetting method includes the step of receiving the diameter expansion scheduled portion 2 of the raw material 1 by the receiving portion 13 of the receiving die 11 and disposing the diameter expansion scheduled portion 2 of the raw material 1 in the insertion hole 23 of the guide 20 and the step of expanding the diameter of the diameter expansion scheduled portion 2 of the raw material 1 exposed between the tip end face 21 a of the guide 20 and the receiving portion 13 of the receiving die 11 by moving the guide 20 in a direction opposite to the pressurizing direction of the diameter expansion scheduled portion 2 of the raw material 1 while pressurizing the diameter expansion scheduled portion 2 of the raw material 1 by the pressurizing means 30 after the disposing step. Therefore, the buckling of the diameter expansion scheduled portion 2 of the raw material 1 can be prevented.

In the first embodiment, since the diameter expansion scheduled portion 2 of the raw material 1 is expanded in diameter in the free diameter expanding space S between the tip end face 21 a of the guide 20 and the receiving portion 13 of the receiving die 11, in detail, the upsetting method and the upsetting apparatus 10A of this first embodiment can be categorized into a free upsetting method and a free upsetting apparatus, respectively.

Furthermore, at the diameter expansion step, the portion 2 a of the diameter expansion scheduled portion 2 of the raw material 1 corresponding to the tip end portion 21 of the guide 20 is locally heated by the heating means 40. As a result, only the portion 2 a among the diameter expansion scheduled portion 2 of the raw material 1 corresponding to the tip end portion 21 of the guide 20 is locally decreased in deformation resistance. Therefore, the molding pressure can be decreased.

On the other hand, the portion 2 b located at the basal end side among the diameter expansion scheduled portion 2 of the raw material 1 will not be heated, therefore the portion 2 b does not decrease in deformation resistance. Therefore, the end portion of the diameter expansion scheduled portion 2 of the raw material 1 is still hard and hardly deformed by the molding pressure imparted by the punch 31. This can prevent the possible molding pressure increase caused by introduction of a part of the material of the diameter expansion scheduled portion 2 into the gap between the punch 31 and the insertion hole 23 of the guide 20. This in turn can prevent a problem that the processing cannot be performed. Furthermore, the possible molding pressure increase caused by the radially outward expansion of the diameter expansion scheduled portion 2 of the raw material 1 in the insertion hole 23 of the guide 20 can also be prevented. Therefore, even in cases where the length of the diameter expansion scheduled portion 2 of the raw material 1 to be inserted in the insertion hole 23 of the guide 20 is long as well as short, the molding pressure can be decreased assuredly.

Furthermore, the heating means 40 is an induction heating means 41 having an induction heating coil 42, and the portion 2 a of each diameter expansion scheduled portion 2 of the raw material 1 corresponding to the tip end portion 21 of the guide 20 is inductively heated by the induction heating coil 42 disposed at the tip end portion 21 of each guide 20. Therefore, the predetermined portion 2 a of the diameter expansion scheduled portion 2 of the raw material 1 can be heated assuredly and very efficiently.

Further, in cases where the prescribed portion 2 a of the diameter expansion scheduled portion 2 of the raw material 1 is heated into a half-molten state by increasing the heating temperature, the molding pressure can be decreased considerably. This upsetting can be categorized into a Thixo molding.

Further, since the tip end portion 21 of each guide 20 is connected to the guide main body 22 via the heat insulating layer 24, the heat of the tip end portion 21 of the guide 20 can be assuredly prevented from being transferred to the guide main body 22. Therefore, it can be assuredly prevented that the portion 2 b of the diameter expansion scheduled portion 2 of the raw material 1 located at the basal side with respect to the tip end portion 21 of the guide 20 is heated.

In addition, at the diameter expansion step, the diameter expansion is performed with the periphery of the insertion hole 23 of the guide main body 22 of the guide 20 cooled by the first cooling means 50. Therefore, the portion 2 b of the diameter expansion scheduled portion 2 of the raw material 1 located at the basal end side of the guide 20 relative to the tip end portion 21 of the guide 20 is prevented from being heated more assuredly.

Further, at the diameter expansion step, both the diameter expansion scheduled portions 2 of the raw material 1 are simultaneously expanded in diameter. This enables efficient production of an upset forged article 5A having diameter expanded portions 6 and 6 formed at both axial side portions.

FIGS. 7 to 9 are explanatory views showing an upsetting apparatus and an upsetting method according to a second embodiment of the present invention.

In FIG. 10, “5B” denotes an upset forged article produced using an upsetting apparatus 10B of the second embodiment. This upset forged article 5B has a bar-shaped shaft portion 7 and approximately hexagonal plate-shaped diameter expanded portions 6 formed at both axial side portions of the shaft portion 7. Each diameter expanded portion 6 is a portion to be subjected to after processing to produce a connecting portion (e.g., bush mounting portion) to be connected to another member. As such after processing, for example, hole forming processing for forming a bush mounting holding hole in the diameter expanded portion 6 can be exemplified. In the present invention, the shape of the diameter expanded portion 6 is not limited to a polygonal shape such as an approximately hexagonal shape, and can be, for example, a round plate shape or a columnar shape.

Next, the structure of the upsetting apparatus 10B of this second embodiment will be explained while focusing structures different from those of the upsetting apparatus 10A of the first embodiment.

In the upsetting apparatus 10B of this second embodiment, as shown in FIG. 7, molding portions 14 each having a closed cavity 15 for forming the diameter expansion scheduled portion 2 of the raw material 1 into a designed shape are integrally extended toward the axial end sides from each receiving portion 13 of the receiving die 11. Thus, each receiving portion 13 forms a part of a molding surface of the cavity 15. A holding hole 12 is formed through the receiving die 11 so as to be communicated with both receiving portions 13 and 13, i.e., communicated with both cavities 15 and 15.

This upsetting apparatus 10B is configured to simultaneously expand both the diameter expansion scheduled portions 2 and 2 of the raw material 1 exposed between the tip end face 21 a of each guide 20 and the corresponding receiving portion 13 of the receiving die 11 within the corresponding cavities 15 of the receiving die 11. Therefore, the upsetting method and the upsetting apparatus of this second embodiment can be categorized in a restriction upsetting method and a restriction upsetting apparatus, respectively. The cavity 15 corresponds to the diameter expanding space S in which the diameter expansion scheduled portion 2 of the raw material 1 will be expanded in diameter.

Further, this upsetting apparatus 10B is provided with at least one (two in this embodiment) second cooling means 55 and 55 for cooling the molding surface of each cavity 15 of the receiving die 11. Each second cooling means 55 has a cooling jacket 56 mounted on the right and left side portions of the die 11 so as to cover both the molding portions 14 and 14 of the receiving die 11. And, it is configured to cool the molding surface of each cavity 15 of the receiving die 11 by supplying a cooling liquid such as a cooling water to the cooling jacket 56. The arrow 57 denotes the flow direction of the cooling liquid.

Further, at the axial end portion of each molding portion 14 of this receiving die 14, an insertion hole 16 for inserting the tip end portion 21 of the guide 20 is provided.

The other structure of the upsetting apparatus 10B of this second embodiment is the same as that of the upsetting apparatus 10A of the first embodiment.

Next, the upsetting method using this second upsetting apparatus 10B of the second embodiment will be explained below while focusing the points different from the upsetting method of the first embodiment.

In this second embodiment, initially, as shown in FIG. 7, the non-diameter-expansion scheduled portion 3 of the raw material 1 is disposed in the holding hole 13 of the receiving die 11. Thus, each diameter expansion scheduled portion 2 of the raw material 1 is received by the corresponding receiving portion 13 of the receiving die 11. Further, both the diameter expansion scheduled portions 2 of the raw material 1 are disposed in the insertion holes 23 of the guides 20, and the tip end portion 21 of each guide 20 is inserted in each cavity 15 of the receiving die 11 via the insertion hole 16 [Disposing step of disposing the raw material diameter expansion scheduled portion].

Further, current of a prescribed frequency is supplied to the induction heating coil 42 of each induction heating means 41 by the power source portion 43 to inductively heat the portion 2 a of each diameter expansion scheduled portion 2 of the raw material 1 corresponding to the tip end portion 21 of the guide 20 to a predetermined temperature.

Further, a cooling liquid, such as a cooling water, of a normal temperature is flowed through the cooling liquid passage 51 of the guide main body 22 of each guide 20 to cool the periphery of the insertion hole 23 of the guide main body 22.

Further, a cooling liquid, such as a cooling water, of a normal temperature is flowed through the cooling jacket 56 of the second cooling means 55 to cool the molding surface of each cavity 15 of the receiving die 11 to a predetermined temperature.

In this case, the preferable cooling temperature range is, for example, 30 to 80° C. (more preferably 30 to 60° C.). In the present invention, however, it is not required that the cooling temperature falls within the ranges.

Next, while keeping this state, each guide 20 is moved in a direction opposite to the pressurizing direction of the corresponding diameter expansion scheduled portion 2 of the raw material 1 by the guide driving means 27 while simultaneously pressurizing both the diameter expansion scheduled portions 2 of the raw material 1 with the corresponding punch 31 of the pressurizing means 30. Thus, as shown in FIG. 8, both the diameter expansion scheduled portions 2 of the raw material 1 exposed between the tip end surface 21 a of each guide 20 and the corresponding receiving portion 13 are expanded in diameter in the corresponding cavity 15 of the receiving die 11 respectively. [Diameter expansion step].

At this diameter expansion step, by moving the guide 20 in a direction opposite to the pressurizing direction while pressurizing each diameter expansion scheduled portion 2 of the raw material 1 in the axial direction, as shown in FIG. 8, the material of each diameter expansion scheduled portion 2 of the raw material 1 will be filled sequentially in the cavity 15 of the receiving die 11.

Then, as shown in FIG. 9, when the material of each diameter expansion scheduled portion 2 of the raw material 1 is filled in the entire cavity 15 of the receiving die 11 and each diameter expansion scheduled portion 2 of the raw material 1 is formed into a designed shape, the movement of the guide 20 and the pressurization by the punch 31 are stopped.

Thereafter, by taking out the raw material 1 from the receiving die 11, a desired upsetting article 5B as shown in FIG. 10 can be obtained.

The diameter expanded portion 6 of the obtained upset forged article 5A as a preform is subjected to after processing according to need.

Thus, the upsetting method of this second embodiment exerts the following effects in addition to the effects by the upsetting method of the first embodiment.

At the diameter expansion step, the diameter expansion is performed in a state in which the molding surface of each cavity 15 of the receiving die 11 is cooled by the cooling jacket 56 of the second embodiment 55. Therefore, the crystal growth in the diameter expansion scheduled portion 2 of the raw material 1 within each cavity 15 can be restrained.

Further, heating of the portion 2 a of the diameter expansion scheduled portion 2 of the raw material 1 corresponding to the tip end portion 21 of the guide 20 enhances the plastic flow of the material of the diameter expansion scheduled portion 2. As a result, even in cases where the configuration of the cavity 15 is complicated, the material of the diameter expansion scheduled portion 2 can be sequentially filled in the cavity 15 under a lower molding pressure, and a diameter expanded portion 6 having no material-lacked portion can be formed.

In the first embodiment and the second embodiment, in either case, the portion 2 a of each diameter expansion scheduled portion 2 of the raw material 1 corresponding to the tip end portion 21 of the guide is directly inductively heated by each induction heating coil 42. In the present invention, however, it can be configured to inductively heat the tip end portion 21 of the guide 20 by each induction heating coil 42 to heat the portion 2 a of the diameter expansion scheduled portion 2 of the raw material 1 corresponding to the tip end portion 21 of the guide 20. In this case, the predetermined portion 2 a of the diameter expansion scheduled portion 2 of the raw material 1 can be heated assuredly and efficiently. Furthermore, in this case, the tip end portion 21 of the guide 20 is preferably made of a hard conductive material having heat resistance (e.g., heat resistant metallic material) such as steel material.

Although several embodiments of the present invention were explained above, the present invention is not limited to these embodiments and can be modified in various manner.

For example, in the aforementioned embodiment, the non-diameter-expansion scheduled portion 3 of the raw material 1 is disposed in the holding hole 12 of the receiving die 11 and the diameter expansion scheduled portion 2 of the raw material 1 is received by the receiving portion 13 of the receiving die 11. In the present invention, however, in cases where a raw material 1 has no non-diameter-expansion scheduled portion 3, or the entire raw material 1 is a diameter expansion scheduled portion 2, without providing the holding hole 12 of the receiving die 11, the diameter expansion scheduled portion 2 of the raw material 1 can be received by the receiving portion 13 as follows. That is, it can be configured such that the end portion of the raw material 1 is brought into contact (preferably, pressure-contact) with a receiving portion 13 so that the raw material 1 is disposed approximately perpendicular to the receiving portion 13.

Furthermore, in this embodiment, the heating means 40 is an induction heating means 41 having an induction heating coil 42. In the present invention, however, the heating means 40 is not limited to an induction heating means 41, and can be any other means, such as, e.g., an electrical heating means for electrically heating only the tip end portion 21 of the guide 20. In this case, the predetermined portion 2 a of the diameter expansion scheduled portion 2 of the raw material 1 will be heated via the tip end portion 21 of the guide 20.

In the aforementioned embodiments, the pressurizing means 30 has a punch 31. In the present invention, however, the pressurizing means 30 is not limited to a member having a punch 31, and can be a member configured to move a gripping portion for gripping the raw material 1 so as to pressurize the diameter expansion scheduled portion 2 of the raw material 1 in the axial direction with the raw material 1 gripped by the gripping portion or any other means.

Furthermore, in the aforementioned embodiments, the raw material 1 has two diameter expansion scheduled portions 2. In the present invention, however, the raw material 1 can have a single diameter expansion scheduled portion 2 at the axial one side portion of the raw material 1 or at the axial central portion thereof. In this case, the number of the receiving portion 13 of the receiving die 11 or that of the cavity 15 can be one.

In the present invention, the diameter expansion processing can be terminated with a part of the diameter expansion scheduled portion 2 of the raw material 1 remained in the insertion hole 23 of the guide 20. As shown in the aforementioned embodiments, the diameter expansion processing can be terminated immediately after extruding the entire diameter expansion scheduled portion 2 from the insertion hole 23 of the guide 20 into the diameter expanding space S.

Needless to say, the upsetting method and the upsetting apparatus according to the present invention are not limited to a method or an apparatus for manufacturing a preform for a vehicle arm and can be used to manufacture various industrial product preforms, such as, e.g., a shaft preform, a frame preform, a connecting rod preform, a conform for a single head piston or a double-headed piston, or can also be used to manufacture a round-plate shaped forging raw material.

EXAMPLE

Next, concrete examples and comparative examples of the present invention will be explained.

Example 1 and Comparative Example 1 and 2

A bar-shaped raw material 1 made of aluminum alloy (material: A6061) having a diameter of 12 mm was prepared. The diameter expansion scheduled portion 2 of the raw material 1 was expanded in diameter under the conditions shown in Table 1 in accordance with the upsetting apparatus 10A and the upsetting method of the aforementioned first embodiment. The molding pressures required to the processing were investigated. The results are shown in Table 1.

In this case, as shown Table 1, the length of the diameter expansion scheduled portion 2 of the raw material 1 in Example 1 was 200 mm, and the lengths thereof were 150 mm and 200 mm in comparative Examples 1 and 2, respectively.

TABLE 1 Length of diameter Heating Cooling expansion Heating temper- or Not- Molding scheduled portion manner ature cooling pressure Example 200 mm Partial 500° C. Cooling 8.0 × 10⁷ 1 heating Pa Comp. 150 mm Entire 400° C. Not- 7.1 × 10⁸ Ex. 1 heating cooling Pa Comp. 200 mm Entire 400° C. Not- Unable to Ex. 2 heating cooling process

In the column “Heating manner” in Table 1, “Partial heating” means that the portion 2 a of the diameter expansion scheduled portion 2 of the raw material 1 corresponding to the tip end portion 21 of the guide 20 was locally inductively heated by an induction heating coil 42. “Entire heating” means that the entire raw material 1 was heated to a predetermined temperature by a heating furnace and thereafter the raw material 1 was immediately set to the upsetting apparatus and subjected to diameter expansion processing.

“Cooling or Not-cooling” means whether the periphery of the insertion hole 23 of the guide main body 22 was cooled by the first cooling means 50. In this cooling, water of a normal temperature was used as the cooling liquid. The cooling temperature was 40° C.

As shown in Table 1, in Comparative Example 1, the length of the diameter expansion scheduled portion 2 of the raw material 1 was 150 mm. In this case, the molding pressure was 7.1×10⁸ Pa which was very high. In Comparative Example 2, the length of the diameter expansion scheduled portion 2 of the raw material 1 was 200 mm. In this case, the molding pressure exceeded the maximum driving performance of the punch driving portion 32 in the middle of the processing. As a result, the processing could not performed. The reasons are as follows. That is, by pressurizing the diameter expansion scheduled portion 2 of the raw material 1 with the punch 31, the end portion of the diameter expansion scheduled portion 2 of the raw material 1 pressurized with the punch 31 was crushed in the insertion hole 23 of the guide 20 by the molding pressure from the punch 31. Furthermore, since the entire raw material 1 was heated, the end portion of the diameter expansion scheduled portion 2 was deteriorated in deformation resistance. Therefore, the end portion of the diameter expansion scheduled portion 2 became to be more easily crushed. Thus, a part of the material of the diameter expansion scheduled portion 2 was considerably introduced into the gap between the punch 31 and the insertion hole 23. As a result, the molding pressure was increased and exceeded the maximum driving performance of the punch driving portion 32.

To the contrary, in Example 1, the length of the diameter expansion scheduled portion 2 of the raw material 1 was 200 mm which was the same as in Comparative Example 2. In this case, however, the molding pressure was 8.0×10⁷ Pa. Therefore, it was confirmed that the molding pressure can be decreased significantly.

This application claims priority to Japanese Patent Application No. 2005-330528 filed on Nov. 15, 2005, the entire disclosure of which is incorporated herein by reference in its entirety.

It should be understood that the terms and expressions used herein are used for explanation and have no intention to be used to construe in a limited manner, do not eliminate any equivalents of features shown and mentioned herein, and allow various modifications falling within the claimed scope of the present invention.

While the present invention may be embodied in many different forms, a number of illustrative embodiments are described herein with the understanding that the present disclosure is to be considered as providing examples of the principles of the invention and such examples are not intended to limit the invention to preferred embodiments described herein and/or illustrated herein.

While illustrative embodiments of the invention have been described herein, the present invention is not limited to the various preferred embodiments described herein, but includes any and all embodiments having equivalent elements, modifications, omissions, combinations (e.g., of aspects across various embodiments), adaptations and/or alterations as would be appreciated by those in the art based on the present disclosure. The limitations in the claims are to be interpreted broadly based on the language employed in the claims and not limited to examples described in the present specification or during the prosecution of the application, which examples are to be construed as non-exclusive. For example, in the present disclosure, the term “preferably” is non-exclusive and means “preferably, but not limited to.” In this disclosure and during the prosecution of this application, means-plus-function or step-plus-function limitations will only be employed where for a specific claim limitation all of the following conditions are present in that limitation: a) “means for” or “step for” is expressly recited; b) a corresponding function is expressly recited; and c) structure, material or acts that support that structure are not recited. In this disclosure and during the prosecution of this application, the terminology “present invention” or “invention” may be used as a reference to one or more aspect within the present disclosure. The language present invention or invention should not be improperly interpreted as an identification of criticality, should not be improperly interpreted as applying across all aspects or embodiments (i.e., it should be understood that the present invention has a number of aspects and embodiments), and should not be improperly interpreted as limiting the scope of the application or claims. In this disclosure and during the prosecution of this application, the terminology “embodiment” can be used to describe any aspect, feature, process or step, any combination thereof, and/or any portion thereof, etc. In some examples, various embodiments may include overlapping features. In this disclosure and during the prosecution of this case, the following abbreviated terminology may be employed: “e.g.” which means “for example;” and “NB” which means “note well.”

INDUSTRIAL APPLICABILITY

The present invention can be applied to an upsetting method and an upsetting apparatus used in manufacturing a product, such as, e.g., an arm or a piston for vehicles (e.g., cars, or railroad vehicles). 

1. An upsetting method using a receiving die having a receiving portion and a guide having an insertion hole for inserting and holding a diameter expansion scheduled portion of a raw material in a buckling prevented state and in an axially slidable manner and a raw material outlet portion which is one end opening of the insertion hole provided at a tip end face of the guide, the upsetting method comprising: a step of receiving the diameter expansion scheduled portion of the raw material by the receiving portion of the receiving die and disposing the diameter expansion scheduled portion of the raw material in the insertion hole of the guide; and a step of expanding a diameter of the diameter expansion scheduled portion of the raw material exposed between the tip end face of the guide and the receiving portion of the receiving die by moving the guide in a direction opposite to a pressurizing direction of the diameter expansion scheduled portion of the raw material while pressurizing the diameter expansion scheduled portion of the raw material with a pressurizing means in an axial direction, after the step of disposing the diameter expansion scheduled portion of the raw material, characterized in that, at the diameter expansion step, the diameter expansion is performed in a state in which a portion of the diameter expansion scheduled portion of the raw material corresponding to a tip end portion of the guide is locally heated by the heating means.
 2. The upsetting method as recited in claim 1, wherein the heating means is an induction heating means having an induction heating coil, and wherein, at the diameter expansion step, the diameter expansion is performed in a state in which the portion of the diameter expansion scheduled portion of the raw material corresponding to the tip end portion of the guide is inductively heated with the induction heating coil arranged at the tip end portion of the guide.
 3. The upsetting method as recited in claim 1, wherein the heating means is an induction heating means having an induction heating coil, and wherein, at the diameter expansion step, the diameter expansion is performed in a state in which the portion of the diameter expansion scheduled portion of the raw material corresponding to the tip end portion of the guide is heated by inductively heating the tip end portion of the guide with the induction heating coil arranged at the tip end portion of the guide.
 4. The upsetting method as recited in claim 2 or 3, wherein the tip end portion of the guide having the induction heating coil is connected to a main body of the guide via a heat insulating layer.
 5. The upsetting method as recited in claim 1, wherein, at the diameter expansion step, the diameter expansion is performed in a state in which the portion of the diameter expansion scheduled portion of the raw material corresponding to the tip end portion of the guide is heated into a half molten state.
 6. The upsetting method as recited in claim 1, wherein, at the diameter expansion step, the diameter expansion is performed in a state in which an inner surface of a portion of the insertion hole located at a basal end side of the guide relative to the tip end portion of the guide is cooled with a first cooling means.
 7. The upsetting method as recited in claim 1, wherein a molding portion having a cavity for molding the diameter expansion scheduled portion of the raw material into a designed shape is extended from the receiving portion of the receiving die, wherein, at the step of disposing the diameter expansion scheduled portion of the raw material, the diameter expansion scheduled portion of the raw material is received by the receiving portion of the receiving die, the diameter expansion scheduled portion of the raw material is disposed in the insertion hole of the guide, and the tip end portion of the guide is disposed in the cavity of the receiving die, and wherein, at the diameter expansion step, the diameter expansion scheduled portion of the raw material exposed between the tip end face of the guide and the receiving portion of the receiving die is expanded in diameter in the cavity of the receiving die.
 8. The upsetting method as recited in claim 7, wherein, at the diameter expansion step, the diameter expansion is performed in a state in which a molding surface of the cavity of the receiving die is cooled with a second cooling means.
 9. An upset forged article obtained by the upsetting method as recited in claim
 1. 10. An upsetting method using a receiving die having receiving portions formed at both axial end portions and a holding hole communicating with both the receiving portions for holding a non-diameter-expansion scheduled portion of a raw material and two guides each having an insertion hole for inserting and holding a diameter expansion scheduled portion of the raw material located at an axial end side in a buckling prevented manner and in an axially slidable manner with respect to the non-diameter-expansion scheduled portion of the raw material and each having a raw material outlet portion constituted by one end opening of the insertion hole provided at the tip end face, the upsetting method comprising: a step of receiving each diameter expansion scheduled portion of the raw material by a corresponding receiving portion of the receiving die by disposing the non-diameter-expansion scheduled portion of the raw material in the holding hole of the receiving die and disposing both the diameter expansion scheduled portions of the raw material in the insertion holes of the guide respectively; and a step of simultaneously expanding both the diameter expansion scheduled portions of the raw material exposed between the tip end face of each guide and the corresponding receiving portions of the receiving die by moving each guide in a direction opposite to a pressurizing direction of the corresponding diameter expansion scheduled portion of the raw material while pressurizing both the diameter expansion scheduled portions of the raw material with the pressuring means in the axial direction respectively, characterized in that, at the diameter expansion step, the diameter expansion is performed in a state in which a portion of each diameter expansion scheduled portion of the raw material corresponding to a tip end portion of the guide is locally heated with a heating means.
 11. The upsetting method as recited in claim 10, wherein the heating means is an induction heating means having an induction heating coil, and wherein, at the diameter expansion step, the diameter expansion is performed in a state in which the portion of each diameter expansion scheduled portion of the raw material corresponding to the tip end portion of each guide is inductively heated with the induction heating coil disposed at the tip end portion of each guide.
 12. The upsetting method as recited in claim 10, wherein the heating means is an induction heating means having an induction heating coil, and wherein, at the diameter expansion step, the diameter expansion is performed in a state in which the portion of each diameter expansion scheduled portion of the raw material corresponding to the tip end portion of each guide is heated by inductively heating the tip end portion of each guide with the induction heating coil disposed at the tip end portion of each guide.
 13. The upsetting method as recited in claim 11 or 12, wherein the tip end portion of each guide having the induction heating coil is connected to a main body of the guide via a heat insulating layer.
 14. The upsetting method as recited in claim 10, wherein, at the diameter expansion step, the diameter expansion is performed in a state in which the portion of each diameter expansion scheduled portion of the raw material corresponding to the tip end portion of each guide is heated into a half molten state.
 15. The upsetting method as recited in claim 10, wherein, at the diameter expansion step, the diameter expansion is performed in a state in which an inner surface of a portion of the insertion hole located at a basal end side of each guide relative to the tip end portion of the guide is cooled with a first cooling means.
 16. The upsetting method as recited in claim 10, wherein a molding portion having a cavity for molding the diameter expansion scheduled portion of the raw material into a designed shape is extended from each receiving portion of the receiving die, wherein, at the step of disposing the diameter expansion scheduled portion of the raw material, each diameter expansion scheduled portion of the raw material is received by the receiving portion of the receiving die by disposing the non-diameter-expansion scheduled portion of the raw material in the holding hole of the receiving die, both the diameter expansion scheduled portions of the raw material are disposed in the insertion hole of the guide respectively, and the tip end portions of the guides are disposed in the cavities of the receiving die respectively, and wherein, at the diameter expansion step, both the diameter expansion scheduled portions of the raw material exposed between the tip end face of each guide and each receiving portion of the receiving die are simultaneously expanded in diameter in the corresponding cavity of the receiving die respectively.
 17. The upsetting method as recited in claim 16, wherein, at the diameter expansion step, the diameter expansion is performed in a state in which a molding surface of each cavity of the receiving die is cooled with a second cooling means.
 18. An upset forged article obtained by the upsetting method as recited in claim
 10. 19. An upsetting apparatus, comprising: a receiving die having a receiving portion for receiving a diameter expansion scheduled portion of a raw material; a guide having an insertion hole for inserting and holding the diameter expansion scheduled portion of the raw material in a buckling prevented state and in an axially slidable manner and a raw material outlet portion constituted by one end opening of the insertion hole formed at a tip end face; pressurizing means for pressurizing the diameter expansion scheduled portion of the raw material disposed in the insertion hole of the guide in an axial direction; and guide driving means for moving the guide in a direction opposite to a pressurizing direction of the diameter expansion scheduled portion of the raw material, wherein it is configured such that the diameter expansion scheduled portion of the raw material exposed between the tip end face of the guide and the receiving portion of the receiving die is expanded in diameter, and characterized in that the upsetting apparatus further comprises a heating means for locally heating a portion of the diameter expansion scheduled portion of the raw material corresponding to a tip end portion of the guide.
 20. The upsetting apparatus as recited in claim 19, wherein the heating means is an induction heating means having an induction heating coil, and wherein it is configured to inductively heat the portion of the diameter expansion scheduled portion of the raw material corresponding to the tip end portion of the guide by the induction heating coil disposed at the tip end portion of the guide.
 21. The upsetting apparatus as recited in claim 19, wherein the heating means is an induction heating means having an induction heating coil, and wherein it is configured to heat the portion of the diameter expansion scheduled portion of the raw material corresponding to the tip end portion of the guide by inductively heating the tip end portion of the guide with the induction heating coil disposed at the tip end portion of the guide.
 22. The upsetting apparatus as recited in claim 20 or 21, wherein the tip end portion of the guide having the induction heating coil is connected to a main body of the guide via a heat insulating layer.
 23. The upsetting apparatus as recited in claim 19, wherein the heating means is capable of heating the portion of the diameter expansion scheduled portion of the raw material corresponding to the tip end portion of the guide into a half molten state.
 24. The upsetting apparatus as recited in claim 19, further comprising a first cooling means for cooling an inner surface of a portion of the insertion hole located at a basal end side of the guide relative to the tip end portion of the guide.
 25. The upsetting apparatus as recited in claim 19, wherein a molding portion having a cavity for molding the diameter expansion scheduled portion of the raw material into a designed shape is extended from the receiving portion of the receiving die, and wherein it is configured to expand a diameter of the diameter expansion scheduled portion of the raw material exposed between the tip end face of the guide and the receiving portion of the receiving die within the cavity of the receiving die.
 26. The upsetting apparatus as recited in claim 25, further comprising a second cooling means for cooling a molding surface of the cavity of the receiving die.
 27. An upsetting apparatus, comprising: a receiving die having receiving portions formed at both axial end portions and a holding hole communicating with both the receiving portions for holding a non-diameter-expansion scheduled portion of a raw material; two guides each having an insertion hole for inserting and holding a diameter expansion scheduled portion of the raw material located at an axial end side in a buckling prevented state and in an axially slidable manner with respect to the non-diameter-expansion scheduled portion of the raw material and each having a raw material outlet portion constituted by one end opening of the insertion hole formed at the tip end face; two pressurizing means each for pressurizing the diameter expansion scheduled portion of the raw material disposed in the insertion hole of each guide in the axial direction; two guide driving means each for moving each guide in a direction opposite to a pressurizing direction of the corresponding diameter expansion scheduled portion of the raw material, wherein it is configured to simultaneously expand diameters of both the diameter expansion scheduled portions of the raw material exposed between the tip end face of each guide and the corresponding receiving portion of the receiving die, characterized in that the upsetting apparatus further comprises two heating means for locally heating a portion of each diameter expansion scheduled portion of the raw material corresponding to a tip end portion of the guide.
 28. The upsetting apparatus as recited in claim 27, wherein each heating means is an induction heating means having an induction heating coil, and wherein it is configured to inductively heat the portion of each diameter expansion scheduled portion of the raw material corresponding to the tip end portion of each guide by the induction heating coil disposed at the tip end portion of each guide.
 29. The upsetting apparatus as recited in claim 27, wherein each heating means is an induction heating means having an induction heating coil, and wherein it is configured to heat the portion of each diameter expansion scheduled portion of the raw material corresponding to the tip end portion of each guide by inductively heating the tip end portion of each guide with the induction heating coil disposed at the tip end portion of each guide.
 30. The upsetting apparatus as recited in claim 28 or 29, wherein the tip end portion of each guide having the induction heating coil is connected to a main body of each guide via a heat insulating layer.
 31. The upsetting apparatus as recited in claim 27, wherein each heating means is capable of heating the portion of the diameter expansion scheduled portion of the raw material corresponding to the tip end portion of each guide into a half molten state.
 32. The upsetting apparatus as recited in claim 27, further comprising a first cooling means for cooling an inner surface of a portion of the insertion hole of each guide located at a basal end side of the guide relative to the tip end portion of the guide.
 33. The upsetting apparatus as recited in claim 27, wherein a molding portion having a cavity for molding the diameter expansion scheduled portion of the raw material into a designed shape is extended from each receiving portion of the receiving die, and wherein it is configured to simultaneously expand diameters of both the diameter expansion scheduled portions of the raw material exposed between the tip end face of each guide and each receiving portion of the receiving die within each cavity of the receiving die.
 34. The upsetting apparatus as recited in claim 33, further comprising a second cooling means for cooling a molding surface of each cavity of the receiving die. 